The present invention relates to an image receiving sheet for a thermal transfer recording on which an image can be transferred by heat generated by converting light to heat, particularly, relates to an intermediate transfer medium type image receiving sheet for the thermal transfer image recording.
A method by applying pressure or heating by a thermal head has been put to practical use for forming an image by thermal transfer. Such the method has advantages such as a lowered noise, a simple structure, a free of maintenance and a dry processing. Moreover, a resolving ability of from 400 to 600 dpi can be recently obtained as a result of rising of the density of the thermal head. However, the resolving ability of the usual thermal transfer method is limited to the above since the density of the thermal head is difficultly made higher than the present condition.
From the viewpoint of the above-mentioned, a heat mode laser thermal transfer method has been proposed, in which a light-heat conversion type recording element is imagewise exposed by laser light. The resolution ability can be considerably risen by this method since the diameter of laser beam can be condensed to several micrometers.
A high precision image can be written on an image receiving element used in the light-heat conversion type heat mode recording method. However, the image receiving element has a problem that a sufficient transferred image cannot be obtained when the roughness or undulation of the surface of the image receiving element is large. Accordingly, a process has been proposed for forming an image on a receiving element having a rough surface, in which the image is once transferred on an intermediate transfer element having a smooth surface and the image is retransferred on a desired image receiving element having a rough surface by a method such as laminate.
The image quality can be considerably risen by such the improvement, and the reproduction of a halftone dot can be realized. As a result of that, such the method has been made applicable in the field in which an image similar to a printed image or a photographic image is required.
An example of such the application includes that for a color proof or a color filter.
On the other hand, the light-heat conversion type heat mode recording method includes a method in which a fusible ink or a sublimatable dye is transferred to form an image.
Japanese Patent Publication to Open Public Inspection (JP O.P.I.) No. 6-126993 describes a method by which an image of a sublimatable dye is formed by laser light on an intermediate transferring medium and the image is retransferred to a final receiving element by applying pressure and heat. The image by such the method can be used as a proof of a printing image. In such the application, however, there is a problem that the final color of the image formed by the sublimable dye and that of the image formed by the printing ink are different since color hue reproduction between the dye and the pigment, and together with a problem of spreading of character caused by the different of the gradation at the edge portion of the images formed by the sublimable dye and that of formed by the printing ink.
In contrast to that, the pigment the same as that used in the printing matter can be used in the recording material using the fusible ink image. Therefore such the recording material is considerably suitable for making a proof. Examples of such the suitably usable material include those described in JP O.P.I. Nos. 6-79980, 6-122280, 6-199043 and 9-52458.
Although the image receiving sheet for the laser fusible thermal transfer recording disclosed in such the publications have the merits as above-mentioned. Paper having the surface with a high smoothness such as art paper and coated paper is principally used in such the methods, and the transfer ability of the image to mat paper and high quality paper is not insufficient.
For rising the suitability to such the paper, Japanese Examined Patent Publication No. 7-19052 describes a technique in which a resin layer having a softening point of lower 10xc2x0 C. or more than that of the receiving layer is provided under the receiving layer. Such the embodiment seems advantageous from the viewpoint of the suitability to paper only. It has been confirmed, however, that some problems such as that formation of image defect, lowering in the sensitivity, lacking of the uniformity of image density in the widthwise direction, and formation of ablation, are caused when the above-mentioned embodiments are applied in the high resolution laser thermal transfer recording.
The object of the invention is to provide a receiving sheet for laser thermal transfer recording having a high sensitivity and by which a large size output similar to the printed matter can be constantly obtained with a high fidelity and without any image defect and density fluctuation in the widthwise direction, and the quality of a finally printed matter can be reproduced with high fidelity by transferring the image on paper the same as that to be used for the practical printing. Further object of the invention is to provide a thermal transfer recording method using the image receiving sheet as the intermediate transfer medium.
The invention and its embodiment are described.
An image receiving sheet for thermal transfer recording comprising a support having thereon a lower layer and an image receiving layer are provided in this order from the support, wherein variation of position of point of a needle satisfies the following conditions when the needle having a diameter of 1 mm is touched on the image receiving sheet with a load of 10 g and the temperature is risen at a rate of 5xc2x0 C. per minute;
{(Position at 25xc2x0 C.xe2x88x92Position at 30xc2x0 C.)/Position at 25xc2x0 C.}xc3x97100%xe2x89xa65%
{(Position at 25xc2x0 C.xe2x88x92Position at 130xc2x0 C.)/Position at 25xc2x0 C.}xc3x97100%xe2x89xa750%.
The image receiving sheet wherein variation of position of a point of a needle satisfies the following conditions when the needle having a diameter of 1 mm is touched on the image receiving sheet from which the image receiving layer is removed with a load of 10 g and the temperature is risen at a rate of 5xc2x0 C. per minute;
{(Position at 25xc2x0 C.xe2x88x92Position at 30xc2x0 C.)/Position at 25xc2x0 C.}xc3x97100%xe2x89xa65%
{(Position at 25xc2x0 C.xe2x88x92Position at 130xc2x0 C.)/Position at 25xc2x0 C.}xc3x97100%xe2x89xa750%.
The image receiving sheet of wherein variation of position of a point of a needle satisfies the following conditions when the needle having a diameter of 1 mm is touched on the surface of lower layer of the image receiving sheet with a load of 10 g and the temperature is risen at a rate of 5xc2x0 C. per minute;
xe2x80x83{(Position at 25xc2x0 C.xe2x88x92Position at 30xc2x0 C.)/Position at 25xc2x0 C.}xc3x97100%xe2x89xa65%
{(Position at 25xc2x0 C.xe2x88x92Position at 130xc2x0 C.)/Position at 25xc2x0 C.}xc3x97100%xe2x89xa750%.
The image receiving sheet wherein the lower layer contains a thermoplastic resin having a TMA softening point of less than 100xc2x0 C. and a compound having a melting point of less than 150xc2x0 C.
The image receiving sheet wherein difference between melting point of the thermoplastic resin and TMA softening point of the thermoplastic resin is not less than 50xc2x0 C.
The image receiving sheet wherein content of the thermoplastic resin is not less than 50 weight % with respect to the weight of the lower layer and content of the compound having a melting point of less than 150xc2x0 C. is 10 to 50 weight % with respect to the weight of the lower layer.
The image receiving sheet wherein penetration rate of the needle into the compound having a melting point of less than 150xc2x0 C. at the melting point of the compound is not less than 50 xcexcm/min.
The image receiving sheet wherein the lower layer contains a thermoplastic resin having a TMA softening point of 30 to 100xc2x0 C. and having a melting point of 80 to 150xc2x0 C. and difference between melting point and TMA softening point of the thermoplastic resin is less than 50xc2x0 C.
The image receiving sheet wherein content of the thermoplastic resin is not less than 50 weight % with respect to the weight of the lower layer.
The image receiving sheet wherein the image receiving layer contains a thermoplastic resin and a matting agent.
The image receiving sheet wherein an interlayer is provided between the lower layer and the image receiving layer and the adhesion force between the lower layer and the inter layer is larger than the adhesion force between the interlayer and the image receiving layer.
The image receiving sheet wherein the interlayer has a thickness of from 0.2 to 15 xcexcm and a glass transition point Tg of not less than 80xc2x0 C. or a tensile strength of not less than 3.5 kg/cm2.
The image receiving sheet wherein the interlayer has a thickness of from 0.2 to 15 xcexcm and a glass transition point Tg of 80 to 140xc2x0 C. or a tensile strength of not less than 3.5 to 5.0 kg/cm2.
The image receiving sheet wherein Vickers hardness of the image receiving layer is smaller than that of the lower layer at an ordinary temperature.
The image receiving sheet wherein Vickers hardness of the image receiving layer is smaller than that of the interlayer at an ordinary temperature.
The image receiving sheet wherein thermal transfer is induced by laser light irradiation.
A thermal transfer recording method comprising steps of
contacting an image receiving sheet to an ink sheet,
imagewise-heating of the contacted image receiving sheet and the ink sheet, whereby ink of the ink sheet is transferred imagewise to the image receiving sheet,
separating the ink sheet from image receiving sheet,
contacting the image receiving sheet having transferred ink image to a final transferee, and
transferring the image formed on the image receiving sheet to the final transferee, wherein the image receiving sheet for thermal transfer recording comprising a support having thereon a lower layer and an image receiving layer are provided in this order from the support, wherein variation of position of point of a needle satisfies the following conditions when the needle having a diameter of 1 mm is touched on the image receiving sheet with a load of 10 g and the temperature is risen at a rate of 5xc2x0 C. per minute;
xe2x80x83{(Position at 25xc2x0 C.xe2x88x92Position at 30xc2x0 C.)/Position at 25xc2x0 C.}xc3x97100%xe2x89xa65%
{(Position at 25xc2x0 C.xe2x88x92Position at 130xc2x0 C.)/Position at 25xc2x0 C.}xc3x97100%xe2x89xa750%.
The thermal transfer recording method wherein imagewise-heating of the contacted image receiving sheet and the ink sheet is induced by laser light exposure.
The thermal transfer recording method wherein the image is transferred to the final transferee by transferring the image receiving layer of the image receiving sheet for thermal transfer recording.